1. Field of the Invention
This invention relates to a printing apparatus having a plate discharge mechanism for transporting used printing plates mounted peripherally of a plate cylinder, and discharging the printing plates to a plate discharge station.
2. Description of the Related Art
A known printing apparatus having such a plate discharge mechanism includes transport rollers and transport belts for contacting opposite ends of used printing plates and transporting the printing plates from peripheries of a plate cylinder to a discharge station that stores the printing plates successively stacked one upon the other. This printing apparatus can reduce the space required for the plate discharge station.
However, ink and dampening water remain adhering to the surfaces of the printing plates used in printing. In such a printing apparatus, therefore, when used printing plates are discharged to the plate discharge station, a printing plate already stored in the plate discharge station contracts the ink and dampening water adhering to a next printing plate discharged to the plate discharge station. When such a phenomenon occurs, the viscosity of the ink and dampening water causes a cohesion between the printing plate already stored in the plate discharge station and the next printing plate discharged to the plate discharge station. The cohesion poses a problem of errors in transportation of the printing plates.
Japanese Unexamined Patent Publication No. 2003-266639 describes a printing apparatus including a clamp mechanism for pinching one end of each printing plate and drawing the printing plate. This construction prevents the errors in transportation of used printing plates, thereby reliably discharging the printing plates.
However, the printing apparatus described in the above publication requires the clamp mechanism for pinching an end of each printing plate, a moving mechanism for moving the clamp mechanism toward the plate discharge station from a position for pinching the end of the printing plate peeled from the plate cylinder, and an open/close mechanism for opening and closing the clamp mechanism in the position for pinching the end of the printing plate peeled from the plate cylinder and in the discharge station. Thus, the above printing apparatus is complicated in construction and is costly.